1,183 research outputs found
Modulation of microbial consortia enriched from different polluted environments during petroleum biodegradation
No full textEnvironmental microbial communities are key players in the bioremediation of hydrocarbon pollutants. Here we assessed changes in bacterial abundance and diversity during the degradation of Tunisian Zarzatine oil by four indigenous bacterial consortia enriched from a petroleum station soil, a refinery reservoir soil, a harbor sediment and seawater. The four consortia were found to efficiently degrade up to 92.0% of total petroleum hydrocarbons after 2 months of incubation. Illumina 16S rRNA gene sequencing revealed that the consortia enriched from soil and sediments were dominated by species belonging to Pseudomonas and Acinetobacter genera, while in the seawater-derived consortia Dietzia, Fusobacterium and Mycoplana emerged as dominant genera. We identified a number of species whose relative abundances bloomed from small to high percentages: Dietzia daqingensis in the seawater microcosms, and three OTUs classified as Acinetobacter venetianus in all two soils and sediment derived microcosms. Functional analyses on degrading genes were conducted by comparing PCR results of the degrading genes alkB, ndoB, cat23, xylA and nidA1 with inferences obtained by PICRUSt analysis of 16S amplicon data: the two data sets were partly in agreement and suggest a relationship between the catabolic genes detected and the rate of biodegradation obtained. The work provides detailed insights about the modulation of bacterial communities involved in petroleum biodegradation and can provide useful information for in situ bioremediation of oil-related pollution
Exploring the xenobiotic-degrading bacterial and fungal consortia during the selective enrichment procedure.
No full textLIFE-BIOREST (www.lifebiorest.com) is a EU-project aimed to remediate a soil polluted by PHAs, BTEX and alkanes through the application of selected consortia of fungi and bacteria.
The first phase of the project was focused on the characterization and isolation of the autochthonous microbial community that naturally populates this extreme environment. About 220 fungal and 140 bacterial strains with degrading abilities have been isolated from the polluted soil. Most of the fungal strains belonged to Ascomycetes (mainly Aspergillus, Cladosporium, Fusarium and Scedosporium genera) even though about 20 Basidiomycetes were also isolated. Regarding bacteria, the most abundant genus was Pseudomonas followed by Achromobacter, Stenotrophomonas and Ochrobactrum.
The isolates were obtained by means of a liquid enrichment approach on target contami- nants (naphthalene, pyrene, phenanthrene, benzene, alkanes and oil extracted from the soil): the enrichment lasted 3 weeks, and sub-culturing was carried out once a week. Since the pollution in the sampled soil involved several meters of depth, enrichments were carried out separately using as inoculum homogenized soil samples from the 0-1, the 1-2 and 2-3 m depth. A total of 18 enrichment consortia were produced (6 target contaminants X 3 soil depths) for bacteria and other 18 for fungi, and sampled at day 0, 7, 14 and 21, giving a total of 144 samples. For each of these samples, DNA was extracted, amplified respectively for bacterial (16S) and fungal (ITS) biomarkers, and the resulting amplicons sequenced in Illumina. Results will be presented with the aim of assessing the ecological evolution of the microbial communities (bacteria and fungi) during the selective enrichment procedure in presence of different pollutants
Ecology of bacterial communities during petroleum biodegradation: a molecular analysis on degrading consortia isolated from hydrocarbon polluted soils, sediment and seawater samples
No full textEnvironmental microbial communities are key players in the transformation and miner- alization of hydrocarbon pollutants. The aim of this study was to assess changes in bacterial abundance and diversity during the degradation of Tunisian Zarzatine oil by four indigenous bacterial consortia isolated from different polluted environmental matrix (a petroleum sta- tion soil, refinery reservoir soil, harbor sediment and harbor seawater). The microcosms were inoculated for two months with either a defined bacterial consortium and Zarzatine crude oil as only carbon and energy source. The microbial community dynamics was evaluated weekly in microcosms using Illumina 16S rRNA gene sequencing. An average of 7020 sequences per samples were obtained, the measured coverage was higher than 97% and more than 60% of sequence were correctly classified at species level. Degrading consortia enriched from soil and sediments were dominated by species belonging to Pseudomonas and Acinetobacter gen- era, while in the seawater-derived consortia Dietzia, Fusobacterium and Dicoplana emerged as dominant genera. We identified specific OTUs whose relative abundances bloomed from small to high percentages and were significantly correlated to total petroleum degradation: an OTU classified as Dietzia daqingensis in the seawater microcosms, and three OTUs classified as Acinetobacter venetianus in all two soils and sediment derived microcosms. Interestingly, a comparative analysis showed that this was the same OTU in all 3 microcosms which were derived from consortia isolated from different types (soil or sediment) and location. The work provides detailed insights about the modulation of bacterial communities involved in petroleum biodegradation
Giulia Veronica Varisco
No full textThe headword explains the biography and the contribution of the author Giulia Varisco to the children's literatur
Enrichment procedures for the isolation of xenobiotic-degrading bacterial and fungal strain: a focus on microbial ecology
No full textLIFE-BIOREST (www.lifebiorest.com) is a EU-project aimed at the remediation of a soil polluted by PHAs, BTEX and alkanes through the application of selected consortia of fungi and bacteria.
In the first phase of the project, we have isolated from the polluted soil about 220 fungal and 140 bacterial strains with degrading abilities. Most of the fungal strains belonged to Ascomycetes (mainly Aspergillus, Cladosporium, Fusarium and Scedosporium genera) even though about 20 Basidiomycetes were also isolated. Regarding bacteria, the most abundant genus was Pseudomonas followed by Achromobacter, Stenotrophomonas and Ochrobactrum.
The isolates were obtained by means of a liquid enrichment approach on target contami- nants (naphthalene, pyrene, phenanthrene, benzene, alkanes and oil extracted from the soil): the enrichment lasted 3 weeks, and sub-culturing was carried out once a week. Since the pollution in the test soil involved several meters of depth, enrichments were carried out sep- arately using as inoculum homogenized soil samples from the 0-1, the 1-2 and 2-3 m depth. A total of 18 enrichment consortia were produced (6 target contaminants X 3 soil depths) for bacteria and other 18 for fungi, and sampled at day 0, 7, 14 and 21, giving a total of 144 samples. For each of these samples, DNA was extracted, amplified respectively for bacterial (16S) and fungal (ITS) biomarkers, and the resulting amplicons sequenced in Illumina. Results will be presented with the aim of assessing the ecological evolution of the microbial communities (bacteria and fungi) during the selective enrichment procedure in presence of different pollutants
Acute and chronic effects of Titanium dioxide (TiO2) PM1 on honey bee gut microbiota under laboratory conditions
No full textApis mellifera is an important provider of ecosystem services, and during flight and foraging behaviour is exposed to environmental pollutants including airborne particulate matter (PM). While exposure to insecticides, antibiotics, and herbicides may compromise bee health through alterations of the gut microbial community, no data are available on the impacts of PM on the bee microbiota. Here we tested the effects of ultrapure Titanium dioxide (TiO2) submicrometric PM (i.e., PM1, less than 1 μm in diameter) on the gut microbiota of adult bees. TiO2 PM1 is widely used as a filler and whitening agent in a range of manufactured objects, and ultrapure TiO2 PM1 is also a common food additive, even if it has been classified by the International Agency for Research on Cancer (IARC) as a possible human carcinogen in Group 2B. Due to its ubiquitous use, honey bees may be severely exposed to TiO2 ingestion through contaminated honey and pollen. Here, we demonstrated that acute and chronic oral administration of ultrapure TiO2 PM1 to adult bees alters the bee microbial community; therefore, airborne PM may represent a further risk factor for the honey bee health, promoting sublethal effects against the gut microbiota
Molecular and microbiological insights on the enrichment procedures for the isolation of petroleum degrading bacteria and fungi
No full textAutochthonous bioaugmentation, by exploiting the indigenous microorganisms of the contaminated environment to be treated, can represent a successful bioremediation strategy. In this perspective, we have assessed by molecular methods the evolution of bacterial and fungal communities during the selective enrichment on different pollutants of a soil strongly polluted by mixtures of aliphatic and polycyclic hydrocarbons. Three consecutive enrichments were carried out on soil samples from different soil depths (0–1, 1–2, 2–3 m), and analyzed at each step by means of high-throughput sequencing of bacterial and fungal amplicons biomarkers. At the end of the enrichments, bacterial and fungal contaminants degrading strains were isolated and identified in order to (i) compare the composition of enriched communities by culture-dependent and culture-independent molecular methods and to (ii) obtain a collection of hydrocarbon degrading microorganisms potentially exploitable for soil bioremediation. Molecular results highlighted that for both bacteria and fungi the pollutant had a partial shaping effect on the enriched communities, with paraffin creating distinct enriched bacterial community from oil, and polycyclic aromatic hydrocarbons generally overlapping; interestingly neither the soil depth or the enrichment step had significant effects on the composition of the final enriched communities. Molecular analyses well-agreed with culture-dependent analyses in terms of most abundant microbial genera. A total of 95 bacterial and 94 fungal strains were isolated after selective enrichment procedure on different pollutants. On the whole, isolated bacteria where manly ascribed to Pseudomonas genus followed by Sphingobacterium, Bacillus, Stenothrophomonas, Achromobacter, and Serratia. As for fungi, Fusarium was the most abundant genus followed by Trichoderma and Aspergillus. The species comprising more isolates, such as Pseudomonas putida, Achromobacter xylosoxidans and Ochromobactrum anthropi for bacteria, Fusarium oxysporum and Fusarium solani for fungi, were also the dominant OTUs assessed in Illumina
Ytterbium Disilicate/Monosilicate Multilayer Environmental Barrier Coatings: Influence of Atmospheric Plasma Spray Parameters on Composition and Microstructure
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Ytterbium Disilicate/Monosilicate Multilayer Environmental Barrier Coatings: Influence of Atmospheric Plasma Spray Parameters on Composition and Microstructure
by Giulia Di Iorio,Laura Paglia *ORCID,Giulia PedrizzettiORCID,Virgilio GenovaORCID,Francesco MarraORCID,Cecilia BartuliORCID andGiovanni PulciORCID
INSTM Reference Laboratory for Materials and Surface Engineering, Sapienza University of Rome, Eudossiana 18, 00184 Rome, Italy
*
Author to whom correspondence should be addressed.
Coatings 2023, 13(9), 1602; https://doi.org/10.3390/coatings13091602
Original submission received: 10 August 2023 / Revised: 31 August 2023 / Accepted: 11 September 2023 / Published: 13 September 2023
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Abstract
SiC/SiC ceramic matrix composites (SiCf/SiC CMCs) are regarded as the new materials for the hot-section components of aircraft gas turbine engines, since they have one-third of the density of metallic superalloys, a higher temperature capability, good mechanical strength, and excellent thermal shock resistance. However, high-temperature water-vapor-rich combustion gases can induce severe surface recession phenomena in SiC/SiC leading to component failure. For this reason, it is necessary to design protective coatings, i.e., environmental barrier coatings (EBCs), able to protect the SiC/SiC surface in combustion environments. In the present work, ytterbium monosilicate (Yb2SiO5), stable when exposed to water vapor at high temperatures, and ytterbium disilicate (Yb2Si2O7), characterized by a thermal expansion coefficient closer to that of the substrate, were selected for a multilayer EBC system. EBCs were processed using the atmospheric plasma spray (APS) technique. A set of deposition parameters were tested, varying the power of the torch, and the composition and microstructure of the deposited coatings were studied in terms of porosity, crack density, and post-deposition phase retention by performing SEM, EDS, and XRD analysis. The results allow for the definition of the influence of deposition parameters on the final properties of multilayer EBC coatings
Enterococcus faecalis and Vibrio harveyicolonize low-density polyethylene and biodegradable plastics under marine conditions
No full textConventional plastics and bioplastics are known to accumulate in aquatic ecosystems, emerging as new surfaces for biofilm formation and gene exchanges. On the other hand, the fate of non-conventional bioplastics in the marine environment is still unclear. In this study we have measured, by means of crystal violet test and scanning electron microscopy (SEM), the ability of two model bacteria, Vibrio harveyi and Enterococcus faecalis, to form biofilms on low-density polyethylene (PE), polylactic acid (PLA) and starch-based bioplastic (SBB) surfaces. Experiments were conducted in artificial sea water, incubating squares of 3 cm2 of the three plastics with the two model microorganisms and sampling overnight, and at 3 and 6 days. The presence of biofilms on plastic surfaces was detected from day one of incubation and SBB was the material with the highest biofilm formation. E. faecalis formed the thickest biofilm after 3 days with PLA and SBB, but did not remain stable, and after 6 days with PE. The maximum biofilm formation of V. harveyi was obtained overnight with SBB and PE, and after 3 days with PLA. Our data indicate that both plastic and bioplastics support the formation of biofilms of model pathogenic bacteria, highlighting potential concerns for human health
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